Question Macbook wont boot

[Ciaran92]

my macbook is not booting from my hard drive, its working fine when there is a external hard drive in it with os x on it, and when I install os x through disk utility without the external hard drive, its says its installing but once its finishes it repeats it self and downloads again, any help would be appreciate ?

 

[Gallarian]

Sounds like the boot order is wrong - head into your 'Open Firmware' (BIOS to us PC users) and check the boot order to make sure your HDD is priority.

 

[Ciaran92]

I tired getting to the open firmware on start up with the command option O F but a flashing grey box comes up ?